In patients with cancer, the pharmacokinetics of 4'deoxydoxorubicin and its toxicity and efficacy were determined. We found the pharmacokinetic parameters highy variable, that the aldo-keto reductase product, 4'deoxydoxorubicinol, was the only detectable metabolite in plasma and urine and that other properties differed. We examined secretion of doxorubicin and cisplatin in human milk in a lactating woman with ovarian cancer. Significant amounts of doxorubicin and metabolites were secreted in the milk, but cisplatin was not detected in the milk.